This invention relates to rotary actuators and with the provision of means whereby the angular position of such actuators can be controlled.
The invention is particularly concerned with positioning means for use with a rotary actuator said means comprising a control valve for admitting pressure fluid to the actuator and biasing means acting to urge said control valve to a state in which the fluid pressure will be supplied to the actuator to move it to one end position, the control valve being displaceable against said biasing means by a controlling force to move the actuator away from said position. The positioning means further include feedback means for connection to the actuator to be responsive to said actuator movement for modifying the action of the biasing means on the control valve, whereby the control valve is brought to a neutral position by the resultant action of said feedback and biasing means with said controlling force, said neutral position being obtained at an actuator position dependent upon the magnitude of said controlling force.
One object of the invention is to provide positioning means that can be connected directly to its actuator without external pressure fluid connections.
Another object of the invention is to provide positioning means of a more compact form than has hitherto been obtained.
A further object of the invention is to provide positioning means that comprises a diecast or moulded valve body in which the required fluid conduits are provided in a manner that avoids or reduces the need for subsequent drilling operations in the formation of said conduits and that also avoids or reduces the need for fluid-tight joints to be made between parts of the positioning means itself.